Telephone system



April 26, 1932. A. B. PREuss TELEPHONE SYSTEM Filed April 15, 1931 Inusn :u- Hlexanclsr Bruno Prensa Patentecl Apr. 26, 1932 UNITED sTATEs PATENTl orrres ALEXANDER BRUN PREUSS, OF BERLIN, GERMANY, ASSIGNOR TO SIEMENS & HALSKE AKTIEN'GESELLSGHAFT, OF SIEMENSSTADT, NEAR BERLIN, GERMANY i rntnrnonn d'sYsfriza/r i Application 'file April 15, 1931, 'Serial No.

a simple manner -that a -subscriber whose preselector is set'in aspecial position can be w1:5 called. This is achieved. by .a test circuit, made possible by the free hunting of the final selector, being set up at the setting of the preselector in a special position.

An embodiment of the invention is shown 20 in the clrawing to Which embodiment, however, the invention is not limited.

A preselector is shown in the drawing with which is associated a line relay and a test relay. It is obvious that the arrangement 25 according to the invention can also be used for preselectors with a single relay designed as a two-step rela-y or relay with double ar- V mature.

When the subscriber at the station Tfn, lifts 80 his receiver the following circuit'is set up:

earth, winding I of the repeater device supplying the busy signal, contact tt, line Lb, line loop at the subscribefls station Tn, line La, contact t, relay R, battery, earth. Re-

!6 lay R is energized and actuates contact lr. Hereby the following circuit for the rotary magnet D of the preselector is completed: earth, interrupter rotary magnet D, contact Qt thrown-over contact lr, position C '40 of the switch wiper f of the preselector, battery. earth. The rotary magnet is operated in this circuit and the switch wipers of the preselector are advanced step by step. When the preselector has left the position O the #5 forward stepping circuitis maintained over the contact segment 1-10 of the switch wiper If a free line 'has been found, by way of example the line La 1, the following circuit is completed: earth, not shown switch- 60 ing device, winding IIof relay P, contact 530,322, and in Germany August 26, 1930.

510, contact th of a not shown time switch, line La 1, wiper c of the preselector, windings I and II of relay T, switchwiper e of the preselector, contact lr, segment 1-10v of the switch wiper f, switch wiper f, battery earth. In this circuit the relays P and T are energizedwhereby contactst, t, and 42? are actuated. The forward stepping eircuit for the rotary magnet is broken by contact 225 whereby the preselector is brought to rest. By the throwing over of :contact 2t battery is immediately applied to winding I of relayf-T, with the result that winding VII is disconnected, whereby a guarding is eifected in known manner. i Contacts 325 and tt switch through the subscribefis line. :Belay P ac- Htuate's its contacts 519.- 'If the connection is not fcompleted due to the' subscriber not having dialed within a certain vperiod contact th is opened in known manner, whereby'the test Circuit-"is broken. Relays P Vand T reflease. On the release of relay T 'relay R is re-energized as the line :loop4 atthe Subscriberls station would not yet be open. Contact lr is throwni over;y Further, contact 21? is brought' .to Vits originalr position where-by the following 'forward -stepping Circuit is establis,hecl:,-earth, interrupter ,Vrotary magnet D, contact 2t, vsegment 14-10 of the switch 'Wiper f, battery, earth. The preselector opera-tes and i-s able to set itself to the next vfree line. VVhen'this has taken placein the valready described manner-the preselector, in case the subscriber still maintains the -li-I'ier loop, is advanced to the -neX-t free-line Vafter a certain period in thc'aflreadyl described' manner Vby the opening Vof contact th. This ad- Vance continu'es until the switchwipersof the preselector-'have reached position 11.v l/Vhen this position is reached the forward stepping Circuit isbroken. at switch wiper f of the preselector.

Belay Tis not energized in' this position. By the coutacts St and Lit having taken up thepositions shownl in the drawing, the subscriber receives the busy signal over winding I of the busy signal device. If now the subscriber is called at-the -subscriberls station Tfn, that is to say, -if test voltage is applied to the flinevLc over a final selectorthe I hIso Vao

circuit eXtends as follows: not shown device in final selector, line Lc, contact O in the contact bank of the switch wiper c of the pre-- selector, contact 11 in the same contact bank, switch wiper c, windings I and II of relay T of the preselector, switch wiper e in position 11, battery, earth. Relay T is energized in this circuit and actuates contacts 22%, 325, and 425. By the throwing over of Contacts 32? and 46 the busy signal device is disconnected. By the throwing over of contact 225 no further switch procedures are caused. Only at the release of the connection, that is to say, after the circuit over the line loop and also the circuit for relay T has been broken, can the preselector reach its original position as, by the throwing over of Contacts l'r and 2t into their normal positions, the forward stepping circuit is again established in order to bring the preselector into its original position.

Similar switching operations are eifected when all Outgoing lines are engaged at a call. In such a case the preselector arrives immediately into position 11 in which it will be brought to rest and in which also a call is possible in the already described manner. It should also be mentioned that relays R and T in the above described circuit could be replaced by a single relay, for example, a two-step relay in which the contact 17' would be actuated at the energization of win-ding R, while contacts 2t, 3t, and lit would be actuated at the energization of winding T.

What is clai-med is: 1. In a telephone system, a subscriberis line terminating in a lineswitch, means responsive to an abnormal condition on said line for Operating said switch to a particular position to prevent its connection to other switching apparatus, and means for rendering said line available for incoming calls while said switch is in said position.

2. In a telephone system, a subscribefs line terminating in a. lineswitch, means responsive to an abnormal condition on said line for Operating said switch to a particular position, and a test circuit set up by said switch in said position to allow the associated line to be called.

3. In a telephone system, a subscriber's line terminating in a lineswitch, means responsive to an abnormal condition on said line for operating said switch to a particular position, and a test circuit prepared by said switch in said position to make the line available for incoming calls, said test circuit including the test wiper of said switch and the normal and special position'bank contacts of said test wiper.

4. In a telephone system, a subscriberis line terminating in a lineswitch having a normal position, a test circuit prepared over a test wiper of said switch and its normal bank contact for establishing incoming calls to said line, means for Operating said switch to a Les-5,416

special position responsive to an abnormal condition on said line, and a test circuit prepared Over said test wiper and its special position bank contact to render said line available to ncoming calls when said switch is in said special position.

5. In a telephone system, a subscribefls line terminatingI in a lineswitch, -means responsive to an abnormal condition on said line for Operating said lineswitch to a special position to prevent its connection to other switching apparatus, means for rendering said line available to incoming calls while said condition exists, and means forapplying busy tone to said line while said switch is in said special position and the line is not being called.

6. In a telephone system, a subscriberls line terminating in a lineswitch, means responsive to an abnormal condition on said line for Operating said lineswitch to a special position to prevent its connection to other switching apparatus, and for applying busy tone to said line, a test circuit prepared by said switch in said special position to make the line available to incoming calls, and means in said test circuit for removing said busy tone when an incomingV call is received.

In witness whereof, I hereunto Subscribe my name this 25th day of March, A. D. 1931.

' ALEXANDER BRUNO PRESS.

Iis 

